JP2002331797A - Whiteboard capable of using oil base ink pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new whiteboard wherein drawing and deleting by a pen using an oil based ink can be performed without using a pen using an alcohol based ink, and the deletion even after being left to stand for a long period of time after drawing is easy. SOLUTION: This whiteboard has a hydrophilic swelling layer on a base board, and drawing by an oil based ink and deleting are possible. The whiteboard has a primer layer in addition to the hydrophilic swelling layer. In this case, the primer layer contains a pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a whiteboard, and more particularly, to a whiteboard in which an oil-based pen can be used.

[0002]

2. Description of the Related Art A whiteboard is a writing board that can be drawn with so-called marking ink (marking pen) or the like and can be erased by wiping with a cloth or the like. In addition, a sheet-like white board was invented and cut into a suitable size,
A simple whiteboard that can be attached to any location and used has also been proposed. These traditional whiteboards
Drawing and erasing were possible by using an alcohol-based ink as the marking ink. However, alcohol-based inks have problems such as a lower drawing density than oil-based inks and difficulty in erasing if left for a long time after drawing.

[0003]

SUMMARY OF THE INVENTION According to the present invention, drawing and erasing can be performed with a pen using oil-based ink without using a pen using alcohol-based ink. A new whiteboard that is easy to erase.

[0004]

The whiteboard of the present invention is a whiteboard in which an oil-based ink having a hydrophilic swelling layer provided on a substrate can be drawn and erased.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a whiteboard having a hydrophilic swelling layer on a substrate. By providing the hydrophilic swelling layer, characters and pictures drawn with oil-based ink can be erased by using water. The reason is not always clear, but when water is supplied to the hydrophilic swelling layer, the hydrophilic swelling layer swells greatly, but when viewed in detail, a water film is generated at the interface between the oil-based ink and the hydrophilic swelling layer. However, it is considered that the film allows the oil-based ink to be separated from the hydrophilic swelling layer to enable erasure.

[0006] The hydrophilicity in the present invention means a property that is substantially insoluble in water and exhibits water swellability. In the present invention, a hydrophilic hydrophilic swelling layer is used in which a known hydrophilic polymer is laminated on a substrate by coating or transfer or the like, crosslinked or pseudo-crosslinked using a known method, and insolubilized in water to make water swellable. Can be

The hydrophilic polymer referred to in the present invention means a known hydrophilic polymer (which means completely soluble in water), a pseudo-water-soluble polymer (which means amphiphilic, and macro-soluble in water) Means that the micro contains undissolved parts)
Means That is, it refers to a polymer that adsorbs or absorbs water under normal use conditions, and a polymer that dissolves in or swells in water.

[0008] Known hydrophilic polymers can be used in the present invention, including animal-based polymers,
There are plant-based polymers and synthetic-based polymers. For example, “Functional Monomers (Functional M)
onomers) "(Y. Nyquist, Dekk
er), "Water-soluble polymer" (by Nakamura, Chemical Industries),
Listed in "Latest Processing and Modification Technologies for Water-Soluble Polymers and Application Development of Comprehensive Technical Data" (Management Development Center Publishing Division), "New Water-Soluble Polymer Applications and Markets" (CMC) Hydrophilic polymers. Specific examples of the hydrophilic polymer are described below. (A) Natural polymers starch-acrylonitrile-based graft polymer hydrolyzate, starch-acrylic acid-based graft polymer, starch-styrene sulfonic acid-based graft polymer, starch-
Vinyl sulfonic acid type graft polymer, starch-acrylamide type graft polymer, carboxylated methyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, xanthate cellulose, cellulose-acrylonitrile type graft polymer, cellulose-styrene sulfonic acid type graft polymer , A carboxymethylcellulose-based crosslinked product,
Hyaluronic acid, agarose, collagen, milk casein, acid casein, rennet gasein, ammonia casein, potashized casein, borate casein, glue, gelatin, gluten, soy protein, alginate, ammonium alginate, potassium alginate, sodium alginate Gum, tragacanth gum, karaya gum, guar gum, locust bean gum, Irish moss, soy lecithin, pectic acid, starch, carboxylated starch, agar, dextrin, mannan, etc. (B) Synthetic polymers Polyvinyl alcohol, polyethylene oxide, poly (ethylene oxide-CO-propylene oxide), aqueous urethane resin, water-soluble polyester, ammonium polyacrylate, sodium polyacrylate, polyammonium methacrylate, N-vinyl Carboxylic acid-based polymer, acrylic acid-based copolymer, acrylic emulsion copolymer, polyvinyl alcohol-based crosslinked polymer, sodium polyacrylate-based crosslinked product, saponified polyacrylonitrile-based polymer, hydroxyethyl acrylate-based polymer, hydroxyethyl methacrylate-based polymer, Poly (vinyl methyl ether-CO-maleic anhydride), maleic anhydride-based copolymer, vinylpyrrolidone-based copolymer, polyethylene glycol diacrylate-based crosslinked polymer, Polyethylene glycol dimethacrylate-based crosslinked polymer, polypropylene glycol diacrylate-based crosslinked polymer, polypropylene glycol dimethacrylate-based crosslinked polymer, and the like.

The above hydrophilic polymer may contain monomers or copolymer components having different substituents for the purpose of imparting flexibility or controlling the hydrophilicity, as long as the effects of the present invention are not changed. It is.

Next, a method for crosslinking a hydrophilic polymer will be described.

The hydrophilic swelling layer is formed by crosslinking or pseudo-crosslinking at least one of the above hydrophilic polymers as necessary.
A layer can be formed on a substrate by insolubilizing in water. Usually, the cross-linking reaction is performed by performing a three-dimensional cross-linking reaction using a reactive functional group of the hydrophilic polymer. The cross-linking reaction may be covalent cross-linking or ionic cross-linking.

Examples of the compound used for the crosslinking reaction include known polyfunctional compounds having a crosslinking property, such as polyepoxy compounds, polyisocyanate compounds, polyacryl compounds, polymethacryl compounds, polymercapto compounds, and polyalkoxysilyl compounds. Examples include compounds, polyvalent metal salt compounds, polyamine compounds, aldehyde compounds, and polyvinyl compounds. The crosslinking reaction is carried out by adding a known catalyst to accelerate the reaction.

These hydrophilic polymers may be used alone or in combination with one another for the purpose of maintaining the form of the hydrophilic swelling layer and adjusting the water swelling property.
It can be used as a mixture of more than one species, and it is also possible to blend non-hydrophilic polymers.

The hydrophilic swelling layer may be subjected to heat treatment at the time of coating or after coating to give various heat histories. In this case, even if the constituent components of the hydrophilic swelling layer are the same, water swelling properties such as water absorption and water absorption may change due to the heat history.

For the purpose of improving the adhesion to the lower layer, it is also possible to add a known silane coupling agent, isocyanate compound, catalyst or the like, or to provide an intermediate layer.

The hydrophilic swelling layer used in the present invention preferably has a specific range of water absorption calculated according to the following method.

Water absorption (%) = water absorption (g / m ² ) / hydrophilic swelling layer thickness (g / m ² ) × 100 Here, the water absorption is the hydrophilic swelling applied to a substrate and dried. It means the value of the amount of water that the layer can hold measured by gravimetry. The water absorption was measured according to the following equation. Water absorption (g / m ² ) = W _WET −W _DRY W _DRY : Weight in dry state (g / m ² ) W _WET : Weight after immersion in water (25 ° C.) for 10 minutes (g)
/ M ² )

[Method of Measuring Water Absorption] A white board to be measured is cut into a predetermined area and immersed in purified water at 25 ° C. After immersion for 10 minutes, the excess liquid adhering to the front and back surfaces of the hydrophilic swelling layer of the whiteboard is quickly wiped off with a cloth or the like, for example, "Hize Gauze" (cotton cloth: manufactured by Asahi Kasei Corporation). The swelling weight W _{WET of} is weighed. Thereafter, the printing plate was dried for about 30 minutes at 60 ° C. in an oven, weighed and the dry weight W _{DR Y.}

The thickness of the hydrophilic swelling layer means a value measured by a gravimetric method after the coated layer of the hydrophilic swelling layer applied on the substrate and dried is peeled off. The thickness of the hydrophilic swelling layer was measured according to the following equation. Thickness of hydrophilic swelling layer (g / m ² ) = (W−W ₀ ) / α W: dry weight of cut white board (g) W ₀ : after peeling and falling off hydrophilic swelling layer from W Dry weight (g) α: Measurement area of lithographic printing plate (m ² )

[Method of measuring hydrophilic swelling layer thickness] After cutting a white board to be measured into a predetermined area α, 6
After drying in an oven at 0 ° C. for 30 minutes, the dry weight W is weighed. Thereafter, the white board is immersed in purified water to swell the hydrophilic swelling layer, and the swelling layer is peeled off using a screver or the like. The white board from which the hydrophilic swelling layer has been peeled off is again dried in a 60 ° C. oven for 30 minutes, and the dry weight W ₀ is weighed.

The water absorption of the hydrophilic swelling layer of the present invention is from 5 to 2 from the viewpoints of ink erasability, form retention and drying.
Preferably, it is 000%. When the water absorption is 5% or more, the ink erasability does not decrease, and when the water absorption is 2000% or less, the form retention is high and the hydrophilic swelling layer tends to be hardly damaged during erasing. Further, when the hydrophilic swelling layer holds water, the oily ink is repelled and rendering becomes impossible. Therefore, it is necessary to dry the hydrophilic swelling layer when redrawing is performed after erasing with water.
If it is 000% or less, the time required for drying the hydrophilic swelling layer can be short.

The thickness of the hydrophilic swelling layer is 0.7 to 6.0 g.
/ M ² is preferred. When the thickness is 0.7 g / m ² or more, a uniform hydrophilic swelling layer can be obtained during coating formation, and when the thickness is 6.0 g / m ² or less, drying and heat treatment after coating can be performed. It requires less time and energy and is economically favorable.

The substrate of the whiteboard used in the present invention is not limited at all, except that it must be able to withstand the load applied when drawing with a normal pen. Representative examples include metal plates such as aluminum, copper, and iron; plastic plates such as vinyl chloride, acrylic resin and acrylic butadiene styrene resin; plastic films such as polyester film and polypropylene film; coated paper; and rubber sheets. Can be Further, the substrate may be a composite of the above materials. There is no particular limitation on the thickness of the substrate.

The whiteboard used in the present invention is preferably provided with a primer layer according to the purpose of improving the contrast with the drawn characters and patterns and the adhesive force with the substrate. When providing a primer layer in the whiteboard of the present invention, the following conditions must be satisfied. That is, good adhesion between the substrate and the hydrophilic swelling layer, and good solvent resistance to the solvent of the oil-based ink. Those satisfying such conditions include those containing an epoxy resin as disclosed in JP-B-61-54219, polyurethane resins, phenol resins, acrylic resins, alkyd resins, polyester resins, polyamide resins, melamine resins. , Urea resin, benzoguanamine resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, polyvinyl butyral resin, ethylene
Vinyl acetate copolymer, polycarbonate resin, polyacrylonitrile-butadiene copolymer, polyether resin, polyether sulfone resin, milk casein, gelatin and the like can be used. These resins can be used alone or in combination of two or more.

As the anchor agent constituting the primer layer, a known adhesive such as a silane coupling agent can be used, and an organic titanate is also effective.

In the present invention, as the silane coupling agent contained in the primer layer, a non-basic silane coupling agent is preferably used, and in particular, a vinyl, acrylic or epoxy silane coupling agent is preferably used.

It is optional to add a surfactant for the purpose of further improving coatability.

In order to improve the contrast with ink at the time of drawing, it is preferable that the primer layer contains a pigment, particularly a white pigment, as an additive such as a pigment. As the pigment, titanium oxide, zinc oxide, barium sulfate, calcium carbonate, aluminum oxide, magnesium oxide and the like can be used, and titanium oxide is most preferable.

The amount of the pigment added to the primer layer is 0.5
Preferably, it is about 30.0% by weight. The amount added is 0.
When the content is 5% by weight or more, the contrast with the ink at the time of drawing is sufficiently developed, and when the content is 30% by weight or less, the solvent resistance tends to be hardly reduced due to the addition of the pigment.

The composition for forming the above primer layer is prepared as a composition solution by dissolving in a suitable organic solvent such as DMF, methyl ethyl ketone, methyl isobutyl ketone, dioxane, toluene, xylene and THF. A primer layer is formed by uniformly applying the composition solution on a substrate and heating it at a required temperature for a required time.

The thickness of the primer layer is 0.5
-50 g / m ² is preferable from the viewpoint of the effect of preventing morphological defects on the substrate surface and economical efficiency, and more preferably 1 to 10 g / m ^2.
m ² .

Next, a method for manufacturing a whiteboard according to the present invention will be described.

Using a conventional coater such as a reverse-through coater, an air knife coater, or a Meyer bar coater, or a spin coater such as a whey coater, a composition solution for forming a primer layer composition is formed on a substrate, if necessary. Coating and drying and crosslinking and curing. Next, a whiteboard of the present invention is obtained by applying and drying a composition solution to constitute the hydrophilic swelling layer.

The whiteboard of the present invention can be used as it is as a sheet-like whiteboard, or it can be used after being pasted on a rigid board or the like. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0035]

Example 1 An aluminum substrate (manufactured by Sumitomo Light Metal Co., Ltd.) having a thickness of 0.24 mm was coated with the following primer composition, heat-treated at 200 ° C. for 2 minutes, and dried at 3% by weight.
A primer layer having a thickness of g / m ² was provided. <Primer composition (parts by weight)> (a) 100 parts by weight of epoxy phenol resin "Kancoat" 90T-25-3094 (manufactured by Kansai Paint Co., Ltd.) (b) 10 parts by weight of titanium oxide (c) 800 parts by weight of dimethylformamide Next, the following hydrophilic swelling layer coating solution is applied so as to be the upper layer of the primer layer provided earlier, and then heat-treated at 180 ° C. for 3 minutes, and the hydrophilic swelling layer having a dry weight of 3 g / m ² is obtained. Was applied to obtain a white board.

<Composition of hydrophilic swelling layer (parts by weight)> (1) Hydrophilic polymer [acrylamide-n-butyl methacrylate copolymer (weight composition ratio 70/30)] 80 parts by weight (2) Ethylene glycol diglycidyl ether 15 parts by weight (3) 900 parts by weight of purified water The water absorption of the obtained whiteboard was measured to be 60 parts.
2%. After drawing with "oil pen" PentelPEN (manufactured by Pentel Pen), when wiping and erasing with a cotton pad soaked in water was attempted, erasing was possible.
The oil-based ink could be completely removed. Further, after the drawing was left for 7 days and the above was attempted to be erased by the same method, the same degree of erasing was possible.

Comparative Example 1 "Whiteboard" FB-23
Wc (manufactured by KOKUYO Co., Ltd.) and “Oil Pen” Pentel
After drawing with PEN (Pentel Pen), when trying to erase using "Eraser for Whiteboard" RA-12NB (Kokuyo Co., Ltd.), the drawn ink spreads and it is impossible to erase completely. I could not do it.

[0038]

According to the present invention, drawing and erasing can be performed with a pen using an oil-based ink without using a pen using an alcohol-based ink. A new whiteboard that is easy to use is obtained.

Claims (3)

[Claims] 1. A whiteboard having a hydrophilic swelling layer on a substrate, wherein oil-based ink can be drawn and erased. 2. The whiteboard according to claim 1, further comprising a primer layer. 3. The whiteboard according to claim 2, wherein the primer layer contains a pigment.